#include <stdio.h>
#include <assert.h>
char* my_strncat(char* dest, char* src, size_t num)
{
	assert(dest && src);
	char* ret = dest;
	while (*dest)
	{
		dest++;
	}
	while (num-- && *src)
	{
		*dest++ = *src++;
	}
	return ret;
}
int main()
{
	char str1[20] = "Hello ";
	char str2[] = "World";
	printf("%s\n", my_strncat(str1, str2, 5));
	return 0;
}